class_docstr: Named entity.
class_docstr_tok: ["Named","entity","."]
code: def test_count_sentences_missing_value(self):
      s = pd.Series(["Test.", np.nan])
      self.assertRaises(TypeError, nlp.count_sentences, s)
  
file_path: texthero/tests/test_nlp.py
imports: import pandas
  import numpy
  from texthero import nlp
  from .None import PandasTestCase
  import doctest
  import unittest
  import string
label_desc: Use image node_id 5 for calling the TestNLP obj's underlying member method code with example usage: obj.test_count_sentences_missing_value() without return types